Your claim was that there is a 555 in the CS amps. Whether or not a small amount of clipping is audible is a separate issue. There is no 555 in these amps. I verified that by looking at the drawings for all the CS series - CS400,800,900, 1000, 1200. ANd among those are several variants. Not one has a 555. My shop has been a Peavey authorized service center for 18 years, and at no time have I seen a 555 in any of their power amps.

The DDT is level activated, so it does nothing until the threshold is reached. Can you beat it with a fast pulse? Probably. Most peaks are bottom and and they round off very nicely.

It all depends on what you want to do with the amp. As a touring musician, the Peavey stuff is quite reliable and sturdy, it can be serviced anywhere in the world, the company still stands behind products that are 30 years old. I can still buy parts for most anything they ever made. You get a lot more amp for your money than buying some other brand, and their customer support is head and shoulders above anyone else in the business. My shop is authorized by most of the major brands, so I work with all the makers. Peavey is consistently the most supportive.

It may not be hifi, but for playing music in clubs it works well. Other popular brands like Crown and QSC make fine products too, but they tend to be more esoteric and complex and service facilities are fewer and farther between. Brands like Mackie I don't even want to work on.

If you refer to a small - perhaps 60mm on a side? - board on the bottom, it is a zener regulated supply for the low voltage circuits.

There are not a lot of boards in the amps. The heat sink assemblies have the power transistors, and a driver board mounts to the underside of that, one for each channel. There are no other boards. I am sorry, there is a small board on the front for each volume control.